@proceedings {351,
title = {The influence of ductile structure and rheological heterogeneity on brittle structures as exhibited by Avalonian granites in southeastern Massachusetts},
volume = {40},
year = {2008},
month = {03/2008},
pages = {3},
publisher = {Geological Society of America (GSA) : Boulder, CO, United States},
edition = {2},
address = {Buffalo, NY},
abstract = {The orientation and geographic distribution of joints, veins, and brittle faults show a conspicuous correlation with the heterogeneous distribution of foliation and lineation intensity in Neo-Proterozoic granites and their deformed counterparts in southeastern Massachusetts. Field mapping and stereonet analysis of brittle and ductile structural data collected during 1:24,000-scale geologic mapping of the Milford quadrangle yielded the following general observations, which suggest that the ductile deformational history of this region appears to have strongly influenced the later development of brittle structures in the same rocks:

The above regional joint sets rotate into parallelism with lithologic and structural heterogeneities such as diabase dikes, shear zones, or xenoliths. Such features commonly have local joint sets parallel to them.

Where the granites display a strongly developed fabric, the dominant joint sets are parallel and orthogonal to foliation and perpendicular to a pervasive northeast plunging lineation.

Nearly all fractures observed that are not parallel to foliation, or part of the regional joint sets mentioned above, are either parallel or perpendicular to the regional lineation.

Well Inventories consist of ESRI ArcView Project files (*.apr), associated ESRI shapefiles and scanned boring logs compiled from several sources. \ Each *. apr file displays borehole locations, information about the boring itself, and, where available, a scanned image of the boring log.\ Be sure to read the "README.TXT" file before using this product.

This map shows the stacked vertical distribution of nonlithified surficial earth materials within the Marlborough quadrangle. This series of maps shows these deposits as they are vertically arranged in units from bottom to top. Surficial materials include mineral and rock particles in glacial deposits, and mineral, rock, and organic particles in postglacial deposits. Surficial materials also are known in engineering classifications as unconsolidated soils, which include coarse grained soils, fine grained soils, or organic fine grained soils. Surficial materials underlie and are the parent materials of modem pedogenic soils which have developed in them at the land surface. Delineation of the materials is based on surficial geologic mapping (Stone, 1978, Hildreth, 2003, 2004), the identification of glacial meltwater morphosequence deposits, knowledge of the deglaciation history of New England, and examination of borehole logs and water well records. For this set of maps, glacial meltwater deposits are distinguished by their geomorphologic expression, sediment type, and depositional environment. These deposits are further subdivided into a series of related glacial sedimentary facies, which are stacked vertically within each glaciaodeltaic or lake-bottom deposit. Postglacial deposits at the land surface are differentiated by their sediment type and geomorphic expression. The principal surficial materials map shows the distribution of these materials exposed at land surface. The smaller inset maps (maps A-F) show the surface and subsurface distribution of the glacial meltwater deposits , including the distribution of specific sedimentary facies that compose these meltwater deposits. By using each inset map in sequence both the lateral extent and vertical arrangement of the deposits at a particular location can be estimated from bottom to top.

This map integrates well-drilling data with surficial geologic mapping and bedrock geology to produce a true three-dimensional model of the subsurface conditions within the Marlborough quadrangle, Massachusetts. The first component of this model is a map depicting a three-dimensional block diagram of the stratigraphic units that overlie the bedrock surface. The map also presents three-dimensional depictions of the individual stratigraphic units, their aerial extent and volumes.

In addition to the map, the supporting grid files, database and documentation for the three-dimensional model are provided.

This three-dimensional model of the subsurface stratigraphy of the Marlborough quadrangle provides a tool to visualize and explore the relationships of the subsurface units to one another, to the underlying bedrock, and to the water bearing fractures within the bedrock.

There are three immediate benefits of this three-dimensional model:

it provides a better estimate of the volume of sand and gravel resources, surpassing current assessments it affords an estimate of the volume of water available in storage, making it a more complete measure of our water assets.

it includes grid files of each stratigraphic unit, which provides a better initial conceptual model of the aquifer systems. The consulting community and water managers can import these grid files into groundwater modeling software for numerical analysis. In addition, the three-dimensional model can better delineate ground water flows, areas of groundwater recharge, and aquifer interconnectedness.

It will also help identify possible contaminant pathways and assist in the placement of ground water monitoring wells. The model can also be used to assist with the planning of major construction projects, assess the impacts from development, provide guidance for land use planning and smart growth initiatives. In total, a three-dimensional model of the subsurface provides critical geologic information for natural resource decision making.